1. Field Of The Invention
This invention relates to the quantified measurement of temperature. More specifically, the invention relates to viscometric thermometers having no metallic components.
2. Prior Art
Conventional thermometric methods and instruments are not suitable for use in strong electric or magnetic fields such as microwave frequencies because of (a) perturbations in the field caused by conductive components of the sensor and/or instrumentation or (b) direct heating of the sensor by the electric or magnetic field. Although techniques have been developed to minimize field effect consequences on thermistor and thermocouple probes, it has proven impossible to completely eliminate such interactions.
Viscometric temperature measurement has origins before the beginning of the twentieth century. U.S. Pat. No. 503,337 issued Aug. 15, 1893 to E. A. Uehling and A. Steinbart describes a device designed to function with viscometric principles albeit the principles themselves are not explained. Conceptively, the technique is predicated on the known relationship between temperature and viscosity for a given fluid medium. Recently, this basic concept has been exploited in two ways. By one procedure, the fluid medium is pumped through a capillary sensing element at a constant flow rate. Temperature is derived as a function of measured pressure differential across the capillary. By the other procedure, the fluid medium is driven through the capillary sensing element by a constant pressure head and temperature is derived as a function of measured flow rate.
The Journal of Bioengineering, Vol. 1, 1977, pp 547-554 publication "The Viscometric Thermometer: A Non-Perturbing Instrument For Measuring Temperature In Tissues Under Electromagnetic Radiation" by M. M. Chen et al describes the theory and implementation of a constant flow rate instrument.
Review of Scientific Instruments, Vol. 55, No. 9, Sept. 1984, pp 1471-1474, in the article "Viscometric temperature measurement in electric or magnetic fields," by J. Seyed-Yagoobi et al describes a constant pressure system of viscometric thermometry.
Although both of the foregoing procedures are accurate and reliable for steady state temperature measurement, transient response is less than desirable.
It is therefore, an object of the present invention to provide a viscometric thermometer having an accurate response interval of 3 to 4 seconds.
Another object of the present invention is to teach a thermetric measuring procedure that utilizes only nonionizing or conductive components in the sensory zone.
Another object of the present invention is the construction of a constant pressure mode viscometric thermometer having improved accuracy and responsiveness.